Tadashi is Here
by IAMGinny
Summary: Tadashi couldn't make himself regret trying to help Professor Callaghan; someone had to help after all. But leaving Hiro? That he regretted more than anything. Well not so much leave, Hiro just didn't know he was still here. AU where Tadashi's spirit ties itself to Baymax. Sporadic updates.
1. Prologue: Hiro

Tadashi couldn't make himself regret trying to help Professor Callaghan; someone had to help after all. But leaving Hiro? That he regretted more than anything. Well not so much leave, Hiro just didn't know he was still here. AU where Tadashi's spirit ties itself to Baymax.

**This will be a multi-chapter fic. I own nothing of Big Hero 6.**

When the text is _italicized_ Tadashi is talking, or it's a flashback.

When "parenthesis" is used Baymax is talking.

When the "_italics_" is in parenthesis Tadashi is talking directly through Baymax.

* * *

Prologue: Hiro

_Tadashi no!_

_Callaghan's in there, someone has to help!_

There was heat.

Then pain, a heavy feeling in his chest.

There was soot, and smoke, and fear, and he _couldn't move._

And then there was nothing.

* * *

Even later, Tadashi wouldn't be able to explain what it felt like to become aware of himself again. He supposed it could be compared to the feeling of waking up from an afternoon nap. A slow, gradual process of waking that left one unaware that they were even awake until they realized they were staring up at the ceiling and had been for a while. The sense of disorientation was familiar, of being oddly disconnected from everything around him.

He'd never much liked that feeling.

Yet it was different from waking up. There was something—other about it. He felt that if he didn't concentrate his entire consciousness on simply _being_ he'd fade away.

So he focused.

_My name is Tadashi Hamada. I go to SFIT._

_I have an Aunt, and friends._

_And a brother, Hiro._

_Hiro._

Hiro. Hiro-Hiro-hirohirohirohirohirohiro_hirohirohirohirohiro_.

Even with the loud crackling of the flames, the incredibly loud roar of the fire, he could here feet smacking the pavement behind him.

_Hiro followed me._

And it was as if this thought brought the shattered pieces back together. Tadashi knew in that moment that he was dead. There was no disbelief. No confusion.

But Hiro, his baby brother, couldn't be dead. Not Hiro.

Not Hiro, who still had so much life in him. Whose only mistake had been following his idiot brother.

_Hiro can't be dead._

He felt a pull in his chest, or more his very being, and at that moment he didn't care if it took him away. As long as it took him to Hiro.

* * *

He really didn't know how he ended up at the San Fransokyo General Hospital. He didn't particularly care.

Aunt Cass was there. She was crying.

His friends sat next to her in the waiting room, Tadashi couldn't tell _which_ waiting room it was.

His heart leapt into his throat.

Aunt Cass rose to her feet, offering the others a teary smile. Tadashi had never seen a smile so forced on his Aunt's face.

"Thanks for coming you guys. I should get back to Hiro. They had to give him something to calm him down, I don't him to wake up alone." Her voice broke halfway through. Honey Lemon pulled her into a hug, even as tears began to stream from her already red and puffy eyes.

In any other moment Tadashi would've thanked Honey, but at the moment all he could process was Hiro.

He was alive.

_I want to see him._

That invisible force tugged at him again, more gently this time. Tadashi didn't fight it, this time he knew for sure that it was taking him to Hiro.

He followed the tug ahead of Aunt Cass and stood in the space between the curtains separating Hiro from the rest of what Tadashi now recognized as the emergency room.

_Hiro._

"Hiro, sweetie. You're awake." Aunt Cass bustled into the room, right through Tadashi. Tadashi didn't even feel it.

"Aunt Cass, where's . . . Where's Tadashi?"

Aunt Cass was crying again.

"Sweetie—"

"He's—he's gone huh?"

"Yeah." It was a croak.

_I'm not. I'm right here._

* * *

The next month went in much the same way for Tadashi.

Hiro and Aunt Cass became the thing he spent all of his time focusing on. Focusing on them just so he would have a reason to stay, to exist.

_I'm scared. I don't want to leave them._

He had to live (figuratively, he thought a bit sarcastically) through his own funeral and the wake.

Professor Callaghan had died too. He hadn't even gotten much past the door before the explosion hit.

He stayed upstairs with Hiro during the wake, only drifting downstairs once or twice to catch a glimpse of his friends.

Hiro withdrew from everyone. Even Aunt Cass couldn't pull him out of it.

Tadashi knew he had to do something when Hiro threw away his acceptance letter.

He just didn't know what he _could_ do.

Until Hiro dropped Megabot on his foot.

"Hello, I am Baymax. Your Personal Healthcare Companion."

* * *

**So tell me what you thought! I know the stream of consciousness is a bit choppy, I did that on purpose because Tadashi has to pretty much be constantly focusing on something. That will change next chapter. It will also follow canon much more closely from now on, I just needed to set things up a bit first.**


	2. Chapter 1: Baymax

**Hey guys, thank you so, so much for following my story! I just finished watching Your Lie in April, so now that I've cried literal buckets, I'm ready to write!**

**I don't own Big Hero 6, any content taken directly from there film isn't mine (obviously).**

**Enjoy!**

* * *

Chapter 1: Baymax

Tadashi sat up from where he'd been lounging on his bed when there was a thunk and Hiro let out an exclamation of pain, peering past the rice-paper wall that separated what Hiro referred to as his "nerd cave" from the rest of the room.

A beep sounded and the next thing he knew, Baymax was inflating over him.

_Baymax. You were here all this time, huh? I forgot that I took you home, Buddy._

Baymax looked down, and then towards the head of the bed—right into Tadashi's face—and for a moment he was sure that Baymax could somehow sense him.

_His sensor? Can he tell I'm here? He has a thermal camera, am I coming up as a cold spot or something?_

But the moment ended quickly, and Baymax turned his head toward the opposite wall. He moved from behind the bed and squeezed between the end of the bed and the dresser, knocking over books in the process.

_Dang it, I know Hiro won't pick those back up._

Baymax waddled over to stop in front of Hiro.

He gave a little wave. "Hell, I am Baymax. Your Personal Healthcare Companion."

Hiro stared at him for a moment. "Uh—hey, Bay-Baymax. I didn't know you were still . . . active."

"I heard a sound of: distress. What seems to be the trouble?"

"Oh I just stubbed my toe a little. I'm fine."

"On a scale of one to ten, how would you rate your pain?"

"Ze-zero? I'm okay really. Thanks. You can shrink now," Hiro assured, holding up his hands in a placating gesture.

"Does it hurt if I: touch it?" Baymax asked as he leaned down, one chubby finger outstretched.

Tadashi figured he should probably help Hiro.

_Maybe I programed Baymax a little too well._

He tried to hold Baymax back—which in hindsight was a bit of a poor attempt to remedy the situation—by grabbing his shoulder and putting himself between Hiro and the well-meaning robot.

_It's fine Buddy, Hiro's not really hurt._

His hand brushed the access port—or not so much his hand, but what he'd equate with his hand if he still had a corporeal form—and yanked it back with a gasp.

_What was that?_

It had felt like a shock. It hadn't hurt, it just felt odd. And left him feeling all tingly.

_I wonder . . . _

Tadashi had heard of cases where spirits affected or even took over technology. Being a man of science he hadn't much believed in them, but . . . here he was. Whatever he was.

He didn't want to possess Baymax though. Baymax was supposed to help people, that's what he was designed for. If he possessed Baymax he didn't know what would happen to the Healthcare Companion programming, he might end up short-circuiting the system.

_But I wrote his programming. And if I could talk to Hiro directly, just for a few minutes . . . _

_I have to try._

He'd written Baymax's programming, so if he could just insert himself into it. . .

He laid his hand once more over the access port, and this time ignoring the tingling even as it became unpleasant, pushed.

* * *

By the time Tadashi had reoriented himself, Hiro was pointing a finger at him and telling him not to scan him.

_Wait . . ._

_He's pointing at me—well Baymax—but me! It worked, I can't believe it worked! And I didn't wreck Baymax!_

It was like Tadashi could breathe again, when he'd forgotten how to. The constant feeling of almost vertigo was gone. His mind was clear. He felt alive again. And more than anything, he wanted to talk to Hiro.

_Hiro! Hiro!_

But Hiro just kept talking.

_He—he can't hear me . . . _

"—hormone and neuro-transmitter levels indicate that you are experiencing mood-swings, common in adolescence."

_Oh, has it finally happened? Is my little baby brother finally becoming a man?_

"Diagnoses: Puberty."

_Uh, Baymax, it was just a joke. Did I make him say that?_

"Wow, what? Okay, time to shrink now." Hiro said, retreating to Tadashi's side of the room.

"You should expect: an increase in body hair. Especially on your: face, chest, armpits, and—"

_Whoa, Bud. Keep it PG._

"Whoa, thank you! That's enough." Hiro exclaimed at the same moment.

"You may also experience powerful new urges."

_I've created a monster . . ._

"Okay! Let's get you back into your luggage," Hiro croaked as he pushed his weight against Baymax in a futile attempt to make him deflate.

_Hey, don't put me in there too! I'm not done trying to talk to you!_

"I cannot deactivate until you say you are satisfied with your care."

_Did Baymax just stall for me?_

"Fine. I'm satisfied with my—whoa!"

There was a load thump, and Tadashi didn't have to try and make Baymax turn around. He did of his own accord.

Hiro was still lying where he landed, digging around under his bed.

He pulled out his favorite blue hoodie and dove into its pocket, pulling out his hand, balled into a fist.

"My microbot? This doesn't make any sense."

_Well, baby brother, you're flowering into manhood, you're gonna be confused. _He couldn't help the jab.

"Puberty can be a confusing time for a young man flowering into manhood."

_Did . . . did Baymax just copy me?_

"The thing's attracted to the other microbots, but that's impossible. They were all destroyed in the fire." Hiro placed the microbot into a petri dish.

_Well what if they weren't?_

"Dumb thing's broken."

_What if it isn't?_

Tadashi wanted to examine the microbot further, but how was he supposed to do that? Could be make Baymax get closer?

Easily Baymax leaned over and picked up the dish, focusing his camera on the small robot inside.

_Did I do that? Or is Baymax just listening to me? But how?_

Tadashi pushed that aside for the moment and studied the microbot.

_I knew it. No matter how I turn it, it points in the same direction. Hiro, your microbot's trying to go somewhere!_

"Your tiny robot is trying to go somewhere."

_That's . . . really creepy. I think I'm talking through Baymax._

"Oh yeah? Maybe you should, ah, figure out where it's trying to go," Hiro answered sarcastically.

_Will that help you start living again? Really living?_

"Will that stabilize your pubescent mood-swings?"

_Close enough._

"Uh-huh. Absolutely."

_Fine then, knucklehead. Anything for you._

* * *

Trying to figure out how to maneuvering Baymax's body was _not_ fun. It wasn't so much maneuver it as get Baymax to go where he wanted to without getting them both—did they count as a both?—run over. He's been able to convince Baymax to follow whatever direction the microbot pointed without much difficulty. But seeing as Baymax had no grasp of how much damage a truck could do to his _own _body—only to a human's—he didn't try to avoid the oncoming traffic.

So when he found a trolley, he told Baymax to get on.

He was aware of Hiro following them through the busy streets and back alleys until they finally came to a stop before an old warehouse in the industrial part of the city.

"Baymax! Are you crazy? What are you doing?" Hiro gasped between breathes; hand on his knees as he caught his breath.

_I found where you microbot was trying to go._

"I have found where you tiny robot wants to go."

"I told you, it's broken, it's not trying to go . . ." Hiro's words halted as he took the petri dish from Baymax's hands and stared down at it.

_That's right, look at it a bit closer knucklehead._

Hiro tried the padlock on the door.

_There's a window._

"There is a window."

* * *

_Geez, you're gunna hurt yourself. Don't step on Baymax's face like that! He's a Healthcare bot, not a stepladder. _

"Please be careful. A fall from this height could lead to bodily harm."

Hiro pulled himself through the window, and Tadashi told Baymax to do the same.

He, of course, got stuck.

"Please wait a moment while I let out some air."

_Is it possible for a ghost to get second-hand embarrassment?_

Hiro pulled them through once Baymax was done. Baymax then had to then _re-_inflate.

_Hiro don't run off! It's dangerous!_

But Hiro was already gone.

They caught up to his brother quickly . . . and proceeded to scare the living daylights out of him.

"You gave me a heart attack!"

"My hands are equipped with defibrillators. Clear."

_I should have worked on his speech processing more . . . _

After Hiro managed to convince Baymax that he wasn't actually in need of resuscitation, he took the microbot from his pocket. It clattered chaotically against its container.

Walls of microbots rose from the bins behind Hiro.

_Ah, crap_

"Oh, no."

Run!"

* * *

**So tell me what you thought! I am writing this as a bit of experience to see if I'd do well in a creative writing class, so I really enjoy the feedback.**

**As for how the Baymax/Tadashi thing, think of it as a symbiotic relationship. Baymax is still perfectly functional, and in control when Tadashi isn't telling/asking him to do things. Tadashi uses the healthcare chip as a way to tie himself to Baymax, and by default, to Hiro.**

**How Tadashi talks through Baymax will be explained next chapter.**

**As time goes on and Tadashi gets used to being a part of Baymax, it'll be easier for him to act through him. **


End file.
